Thermo switch arrangement for control of an internal combustion engine

ABSTRACT

A dual switch is mounted in the wall of the water jacket of the engine so that one thermo switch responds to the engine heat and the other thermo switch responds to the ambient temperature. The switches are connected in series with a source of current and a heater in proximity to an expansible coil controlling the choke valve. The coil is adjacent a water jacket so that it is affected by engine heat. The engine heat responsive thermo switch remains closed until the engine temperature approaches a near-normal value. At low temperatures, the ambient switch is open, and it closes only after the choke is opened following a warm-up period. During cooling of the engine, the ambient switch remains closed down to a relatively low temperature, so that if the engine is &#39;&#39;&#39;&#39;soaked,&#39;&#39;&#39;&#39; the heater will be energized for quick opening of the choke, to relieve the &#39;&#39;&#39;&#39;soak&#39;&#39;&#39;&#39; condition. Another dual thermo switch may be similarly mounted in the wall of the water jacket and connected in a circuit for controlling the ignition advance means of the distributor.

United States Patent Winkley Oct. 21, 1975 THERMO SWITCH ARRANGEMENT FOR CONTROL OF AN INTERNAL COMBUSTION ENGINE Jerry H. Winkley, St. Louis, Mo.

ACF Industries, Incorporated, St. Louis, Mo.

Filed: 0a. 4, 1973 Appl. No.: 403,505

Related US. Application Data Division of Ser. No. 245,759, April 20, 1972, Pat. No. 3,800,767.

Inventor:

Assignee:

References Cited UNITED STATES PATENTS 2/1932 Jarvis 337/370 8/1972 Lenz 123/117 A Primary Examiner-Wendell E. Burns Assistant Examiner-James W. Cranson, Jr.

[57] ABSTRACT A dual switch is mounted in the wall of the water jacket of the engine so that one thermo switch responds to the engine heat and the other thermo switch responds to the ambient temperature. The switches are connected in series with a source of current and a heater in proximity to an expansible coil controlling the choke valve. The coil is adjacent a water jacket so that it is affected by engine heat. The engine heat responsive thermo switch remains closed until the engine temperature approaches a near-normal value. At low temperatures, the ambient switch is open, and it closes only after the choke is opened following a warm-up period. During cooling of the engine, the ambient switch remains closed down to a relatively low temperature, so that if the engine is soaked," the heater will be energized for quick opening of the choke, to relieve the soak condition. Another dual thermo switch may be similarly mounted in the wall of the water jacket and connected in a circuit for controlling the ignition advance means of the distributor.

1 Claim, 4 Drawing Figures US. Patent Oct. 21, 1975 SheetlofZ 3,913,539

I/ll/l/ll I FIGURE 2.

FIGURE l.

FIGURE 3.

FIGURE 4.

THERMO SWITCH ARRANGEMENT FOR CONTROL OF AN INTERNAL COMBUSTION ENGINE This is a division, of application Ser. No. 245,759, filed Apr. 20, 1972, now US. Pat. No. 3,800,767.

BACKGROUND OF THE INVENTION A carburetor choke valve is adapted to close at low temperatures and open after a suitable warm-up period. For this purpose, the choke valve may be controlled by an expansible spiral coil adapted to be heated by the engine coolant or by heatedair. To aid in heating the coil, an electric heater is placed in proximity thereto. Difficulties are oftenencountered when an engine is restarted a short time after it has been shut off, because a condition called soaking" occurs, in which a considerable amount of fuel may condense and accumulate in the intake manifold and the carburetor mixture chamber. The air fuel mixture may then be so rich that starting is very difficult, and if the choke is closed, the excess fuel is not readily removed.

To lower'exhaust emissions, it has been found that at ambient temperatures (say, above about 65F), the ignition should be retarded when the engine is idling. At lower temperatures, it is desirable to advance the ignition for better engine operation. Accordingly, an object of the invention is to achieve desirable operation of the choke valve and of the ignition advance mechanism by means of dual thermo switches responsive to ambient and engine temperatures. 1

SUMMARY OF THE INVENTION Adual purpose switch includes an insulated casing 1 having two widely separated series connected thermo switches therein. The casing is adapted to be mounted in a wall of the water jacketof an internal combustion engine so that a part f the casing is in and a part is outaide the water jacket. The lower or inner thermo switch responds to the engine coolant to control a heater for the automatic choke valve, and its function is to turn the heater off after the engine warms up; The other thermo switch is subject to ambient temperature, and is designed to remain open until choke begins to open. During cooling, after engine shut-down, the ambient switch remains closed down to approximately 60to 66F. If the engine is soaked above 66F, the heater is energized for quick opening of the choke during starting. Below about 60".F, the ambient switch is open, and it does not close until the temperature rises to about 85F. Thus, when starting at a low temperature, the heater is energized only after the choke is opened. Hence, the heater has no effect on the warm-up period, but relieves a soak condition by opening the choke valve.

Another similar dual purpose switch may be mounted in the water jacket to retard the ignition above ambient temperatures of about 65F and advance the ignition at lower temperatures during engine idling. The thermo switch in the water jacket senses any overheating of the engine that might develop due to prolonged idling with loads such as airconditioning applied to the engine.

Under such a condition, the second thermo switch will close to advance the spark and speed up the engine and thereby increase its cooling.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of a switching device having a pair of thermo switches connected in series.

FIG. 2 is a sectional view of a switching device having a pair of thermo switches connected in parallel.

FIG. 3 shows the switching device of FIG. 1 in an arrangement for controlling a choke valve.

FIG. 4 shows an arrangement utilizing the switching device of FIG. 2 for controlling the ignition advance and retard mechanism of a distributor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing, FIG. 1 shows a dual purpose switch 10 including an insulated casing 12 having a threaded member 14 for mounting switch 10 in wall 16 of a water jacket or casing 18 in which the coolant of the internal combustion engine is adapted to flow. The purpose of this arrangement is to convey the heat of the engine to switch 10 so that the lower portion thereof within casing 18 responds to engine temperature. It is evident, of course, that switch 10 may also be heated by the exhaust or by hot air from the engine. Casing 12 contains a pair of widely spaced thermo switches 20 and 22 separated by insulator 23, when necessary. Each thermo switch has an arched disc 24 or 25, and a fixed contact 26 or 27. The bimetallic discs are designed so that they will snap from one arched condition to the opposite arched condition at predetermined temperatures. For example, disc 24 may be designed so that it will snap to its open position at about 65F, and will snap closed at about F. Thermo switch 22 may be designed so that it will snap open at about F. As is evident from FIG. 1, switches 20 and 22 are connected in series between leads 28 and 30.

Referring now to FIG. 3, switch 10 is connected in series with the battery 32 and heater 34. Choke valve 36 is fixed to shaft 38, which is connected to an expansible spiral coil or spring 40 in a well-known manner. Spiral coil 40 is subjected to engine heat and, for this purpose, may be mounted adjacent conduit 42 through which the engine coolant flows. Normally, the opening and closing of choke valve 36, which may be of the unbalanced type, is controlled by spiral coil 40 in response to engine temperature. In the present arrangement, auxiliary heater 34 is also placed in close proximity to spiral coil 40.

The arrangement described above functions as follows: If the ambient temperature is below about 65 F, thermo switch 20 is open and no current is supplied to heater 34. When the engine is started at such temperatures, choke valve 36 is substantially closed and remains in that condition until the engine warms up sufficiently to enable spiral coil 40 to open or permit opening of choke valve 36, in a manner well understood in the art. Choke valve 36 is adapted generally to open at engine temperatures corresponding to ambient temperin water jacket 18 is about 180F, switch 22 will open at about 160F. Thus, heater 34 is cut off during normal engine running.

When the engine is cooling down after being shut-off, switch remains closed at ambient temperatures down to approximately 6066F, and switch 22 closes when it is subjected to. a temperature below about 160F. Hence, if the engine is soaked at ambient temperatures above 66F, the heater will be engergized for quick opening of choke 36 during engine starting. Opening of the choke will, of course, increase the flow of air and help to relieve the soaked condition of the engine to permit starting.

Referring now to FIGS. 2 and 4, switch 50 is similar to switch 10 of FIG. 1 except that thermo switches 52 and 54 are connected in parallel rather than in series. Also, the thermo switches may include a fiat bimetallic strip 56 instead of a bimetallic arched disc. Switch 50 is adapted to be mounted in wall 16 of water jacket 18 in the same manner as is the switch of FIG. 3, and thermo switch 54 is subjected to the engine coolant 58 while thermo switch 52 responds to the ambient temperature. Swtich 50 is connected in series with battery 32 and a solenoid valve 60. Solenoid valve 60 is adapted to control the ignition advance mechanism of a conventional distributor 62. For this purpose, solenoid valve 60 has an outlet comprising conduit 64 connected to air motor 66. The latter may be of a conventional type adapted to advance the spark of distributor 62. As is wellknown, the timing of the ignition is adapted to be responsive to the vacuum in the intake manifold, and this vacuum may be conveyed to motor 66 through solenoid valve 60 by conduit 68. Atmospheric pressure may be supplied to solenoid valve 60 by conduit 70. The purpose of solenoid valve 60 is to apply or remove the intake manifold vacuum from the ignition advance motor 66. In order to improve exhaust emissions, it has been determined that above ambient temperatures of about 65F, the ignition should be retarded at engine idle conditions. At lower temperatures, it is desirable to advance the spark for better engine operation. Hence, thermo switch 52 is designed to close at all temperatures below approximately 65F, and open at temperatures somewhat above that value. The closing of switch 52 energizes the solenoid of valve 60 to permit the vacuum supplied by conduit 68 to be conveyed to motor 66 for advancing the spark. At temperatures somewhat above 65F thermo switch 52 opens and solenoid valve 60 operates to connect to conduit 70 and remove the vacuum from motor 66,

permitting the ignition to be retarded. Switch 56 senses any engine overheating condition that might develop due to prolonged idling with heavy loads such as that of air conditioning. In response to such overheating, switch 56 will close and will operate solenoid valve 60 to permit the vacuum from conduit 68 to be applied to motor 66. Motor 66 will then be actuated to advance the spark, which will speed up the engine somewhat and thereby provide increased cooling of the engine to remedy the overheating condition.

It will be apparent from the foregoing that the invention provides dual bimetallic switch arrangements which facilitate starting a soaked engine and which advantageously control the vacuum operated ignition advance mechanism of a distributor.

What is claimed is:

1. Apparatus for controlling the vacuum responsive spark advance and retard means of an internal combustion engine ignition distributor, comprising a vacuum line from a source of vacuum to said vacuum spark and retard means, a solenoid valve interposed in said vacuum line between said source of vacuum and said vacuum spark and retard means, said solenoid valve also in communication with atmospheric pressure, an elec' trical circuit including a source of current and switch means connected in series with said solenoid valve, said switch means having an elongated casing for mounting said casing in a wall of a container subjected to heat of the said engine, one end of said casing within said wall and the other end of said casing outside said wall, said switch means further including parallel first and second temperature responsive switches, said first temperature responsive switch located inside said casing and outside said wall and responsive to ambient temperature to open above a preselected temperature, said second temperature responsive switch located inside said casing and inside said wall and responsive to engine temperature to close above a preselected temperature, whereby said solenoid valve is energized to apply vacuum to said vacuum spark advance and retard means whenever one of said temperature responsive switches is closed to thereby advance the spark of said ignition distributor and whereby said solenoid valve is deenergized whenever both of said temperature responsive switches are open to thereby communicate said atmospheric pressure with said vacuum spark advance and retard means and thereby retard the spark of said ignitition distributor. 

1. Apparatus for controlling the vacuum responsive spark advance and retard means of an internal combustion engine ignition distributor, comprising a vacuum line from a source of vacuum to said vacuum spark and retard means, a solenOid valve interposed in said vacuum line between said source of vacuum and said vacuum spark and retard means, said solenoid valve also in communication with atmospheric pressure, an electrical circuit including a source of current and switch means connected in series with said solenoid valve, said switch means having an elongated casing for mounting said casing in a wall of a container subjected to heat of the said engine, one end of said casing within said wall and the other end of said casing outside said wall, said switch means further including parallel first and second temperature responsive switches, said first temperature responsive switch located inside said casing and outside said wall and responsive to ambient temperature to open above a preselected temperature, said second temperature responsive switch located inside said casing and inside said wall and responsive to engine temperature to close above a preselected temperature, whereby said solenoid valve is energized to apply vacuum to said vacuum spark advance and retard means whenever one of said temperature responsive switches is closed to thereby advance the spark of said ignition distributor and whereby said solenoid valve is de-energized whenever both of said temperature responsive switches are open to thereby communicate said atmospheric pressure with said vacuum spark advance and retard means and thereby retard the spark of said ignitition distributor. 